Flash memories such as NAND and NOR flash memories have a limited useful life. The cells of the flash memories can be degraded with each programming and erasing operation. One possible cause of the Program/Erase (P/E) cycling degradation of the cells of the flash memories is the trapped charges induced by the cycling of programming and erasing operations.
The P/E cycling degradation of the flash memories includes a shift in the threshold voltage, VT, poor VT distribution, a read margin loss of the multi-level cells and intrinsic charge loss etc.